Jump to content
Silk City Distillers

Continuous Starch Cooking

Recommended Posts

By chance anyone out there utilizing a "continuous" mashing/starch gelatinization process?  I know this is the realm of the big plants.

In an effort to eliminate any and all dust from the mashing process, we've been working on an in-line masher, directly connected to the hammer mill, which will provide for continuous milling, mixing, and heating (utilizing direct steam injection).  Essentially a smaller version of a mill-fed starch cooker.  Instead of conveying grain to the mash ton by air, as we do it today, or even through an auger, we're planning to pump liquid mash at near-gelatinization temps.

Being able to generate continuous mash isn't necessarily the end-goal here, it was to minimize dust and make for an easier and faster mash day.  But, given we have enough clean steam to bring the mash to gel temps in-line, we thought why not just do it all in a single pass.  By the time we're done milling, we're already at temp.  Not to mention we can go down a screen size without creating a disaster of fines.

Thoughts?  Feedback?  Are we crazy?

Share this post


Link to post
Share on other sites

I recall McKee had an article in Artisan Spirit that addressed this topic, although his solution involved milling in the mash tun.

Perhaps McKee will chime in with the issue date, as that article might give you some ideas.

Would like to see some pictures of your inline mashing system when it is complete.

Share this post


Link to post
Share on other sites
34 minutes ago, Jedd Haas said:

I recall McKee had an article in Artisan Spirit that addressed this topic, although his solution involved milling in the mash tun.

Perhaps McKee will chime in with the issue date, as that article might give you some ideas.

Would like to see some pictures of your inline mashing system when it is complete.

Agree that it was a cool article.  I looked into it a little bit.  The process was to use a high shear mixer.  My downside was I already had a mash cooker en route and this would have entailed some substantial modifications.  At the same time, the sales rep I was dealing with for the high shear mixer did not give me great confidence in the whole process.  If you get serious down that route silk, I would fly out and see McKee's.  

 

Side note, the high shear mixer place makes a "high shear pump" that will mill in line, but I am skeptical that it would be able to handle corn.  It was also 50k...

Share this post


Link to post
Share on other sites

We are dry milling so no need for shear mixers.  Expensive and delicate - a stray rock or metal would destroy it.

Approach is more similar to jet cooking, the steam jet provides some additional shear as well to speed gelatinization.

We can probably run the inline cook at 5-7psi, meaning we can hit mash temperatures above atmospheric boiling point.  Depending on the total dwell time this might result in faster gel times.

Our target is around 1000 pounds per hour, which is the top end speed of the hammer mill with corn.

Share this post


Link to post
Share on other sites

Only one I have heard of is Jet Cooker.  That said, are you not concerned about get lots of moisture in your hammer mill?  Trying to picture how I would implement what you are talking about at my place.  Have the milled grain drop into an open pipe with running water that hits a steam injection later down the line?  Going to somehow air gap the shoot down?  Otherwise, you get a backup in that line and you are going to flood your mill...super intrigued by your idea, just don't know how I would try to set it up to get rid of dust...I have a grist hydrator to the mash cooker to get rid of dust in the air, but it does nothing for dust in the auger...

Share this post


Link to post
Share on other sites

Prototype run #2 worked pretty well.

Hammer Mill dust collector directly feeds a completely sealed slurry tank.  The slurry tank contains a water spray injector that feeds water into the mix at a set ratio to our mill speed.  PD lobe pump pulls from the bottom of the slurry tank, and feeds the steam injector assembly, and the mash makes its way into the mash tun.

Trial run was just feeding cold water out of our filtration system, only problem is our water is coming out of the tap at 45f right now.  Didn't help we were running a temporary steam  line as well, undersized, that limited our steam injector flow rates.  So, we were running about 7 gallons a minute slurry through the system, about 15.5 pounds of grain perm minute, going from 45f to 130f out (we were only getting about 300,000btu into the process).

We didn't bother restricting the mash outflow to increase the pressure (and temperature), since we weren't at all near boiling.  Need to swap over to hotter water on the slurry feed, and figure out  what the max temperature we can use before things start gumming up in the slurry tank, and then upsize the steam line for the injector - we're only using half the boiler capacity, so we have some upside.

Need to do some more welding to get all of the components together in a a workable fashion.  I  wish I was a a better tig welder.

Very happy that there is absolutely no dust being liberated.  This was the big issue just using the pneumatic air conveyor from the hammer mill to deliver grain to the dust collector - then drop into the mash tun.  We get a little bit more grain dust being captured in the dust collector, but it's fairly minimal in the grand scheme.

What will be promising is being able to get the slurry to above 220f, where starch gelatinization is very fast.  At that point I can produce 420 gallons of gelatinized mash an hour, for as long as I want to run the mill.

  • reaction_title_1 1

Share this post


Link to post
Share on other sites

Very interesting topic. Been thinking about doing this like the ethanol plants!

Share this post


Link to post
Share on other sites

Originally I was trying to hunt down a jet cooker from Pro-sonix or Hydro-thermal, and when looking at their smaller sanitary designs, realized that there was really nothing all that fancy about them.  All the complexity involved is to just build in enough flexibility to handle different flow rates, viscosities, etc via adjustments to the injector.  Managed to put together a fairly robust steam injector assembly using nearly-off-the-shelf sanitary triclamp parts.

Having to use a lobe pump from the slurry tank,  before the injector, is probably the most costly part of this.  Need to handle a heavy solids feed, and have the ability to deal with the back pressure of the injector and pipeline.

Share this post


Link to post
Share on other sites

Another fairly successful test run today.  Clear, though, that we can't squeeze any more out of this boiler, even tempering the brutally cold ground water, we're still ending up around 140f output, at the 7gpm rate.  Given I'm using the same boiler to heat the water as I'm using to drive the steam injector, should be no surprise since a BTU is a BTU.

Tempted to preheat some water in a holding tank, but that goes against the whole idea.  Once we've got this in a more permanent arrangement, we'll see if we can slow down the mill speed and water flow rates to get closer to boiling.

  • reaction_title_1 1

Share this post


Link to post
Share on other sites

We've run the rig a few dozen times now, and are now using it on every mash.  We're slowly moving to build the permanent setup.  We were a little bit hesitant to pull the trigger on building until we knew we had the kinks worked out.  We ran into an issue last mash, by trying to run the water injection temperature higher than usual (120f) - this caused us to gum up before the steam injection - bad news.  Now we know, the top temperature for water injection is around 80f.  We were mashing oat and corn, and oat has a fairly low gelatinization temperature.

I'll post some pictures later this afternoon of what the current plumbing looks like.  It's not pretty, but R&D sometimes isn't. :)

I am very, very happy.  Zero dust, even when milling to flour - this was the primary goal.  As a result, our batch yield is through the roof compared to the coarse crack we were using to keep the dust down.  We've probably cut a half hour to an hour off our mashing start-to-finish-time.  Running a hammer mill, indoors, with no dust - it's magic.

Share this post


Link to post
Share on other sites

The seagrams plant ran a set up like this for a few years, where they were doing continuous inline cooking and a continuous fermentation. 

Efficiency and infection issues were a regular problem with this continuous system so they eventually went back to doing pressure cooked batches and batch fermentation

Share this post


Link to post
Share on other sites

Yeah, while the approach here is inline starch cooking, it's still very much a batch mash and fermentation process.  Ideally, we're running the inline starch cook around 5-10psi, where we can push the inline temperature to the 220-240 range, above atmospheric boiling, where starch gelatinization is essentially instantaneous.

Share this post


Link to post
Share on other sites

cool setup. What kind of yield are you getting per bushel from this?

Share this post


Link to post
Share on other sites

The costly items are the hammer mill, displacement pump, and a steam boiler big enough to run the whole shebang.  Everything else is incidental.

The static mixer might be kind of spendy, but I don't see why you really need it - generally this type of setup doesn't use it.

The metal fabrication and welding is going to be expensive if you don't have a guy next door that likes to weld.

Share this post


Link to post
Share on other sites

We are running thicker than 3lb/gallon now.

Milling in at 16.6lb per minute with roughly 5.25gal/min of water, for a total volume of 7 gal/min.  Roughly, rye mills faster, corn slower, water pressure fluctuates some.

We've run the water as low as 3gal/min, and it's like extruding thick custard.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...